Gas turbine apparatus



March 16, 1954 A. H. REDDING GAS TURBINE APPARATUS Filed March 12 INVENTOR ARNOLD H. REDDING ATTORN EY Patented Mar. 16, 1954 GAS TURBINE APPARATUS Arnold H. Bedding, Wallingford, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 12, 1951, Serial No. 215,055

4 Claims.

This invention relates to aviation power plants, and more particularly to means for minimizing the adverse effects of formation of ice on the inlet guide vanes of an aviation gas turbine engine.

Various anti-icing devices have been proposed for preventing accumulation of ice on the inlet guide vanes of the compressor of an aviation turbojet or the like, during flight under adverse atmospheric conditions. Currently envisioned methods for de-icing inlet guide vanes generally comprise means for passing hot fluid through internally disposed passages, which may involve use of complicated and costly features of construction. It is an object of the present invention to provide means for mechanically de-icing a compressor inlet guide vane assembly of substantially conventional construction, without necessitating circulation of heated fluid.

Another object of the invention is the provision of means for subjecting the inlet guide vanes of a compressor to an alternating bending stress of suihcient magnitude to cause any ice that forms thereon to break away.

A further object of the invention is the provision of ole-icing apparatus operative to induce vibration of the vane assembly, whereby any ice formed on the vanes will be stressed and dislodged due to the bending moment on the vanes, while inertia forces of the vibrating vanes Will tend to facilitate the shedding of ice.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a diagrammatic longitudinal view, partly sectioned, of a typical aviation gas turbine power plant, the compressor inlet guide vanes of which are associated with one form of de-icing apparatus constructed in accordance with the invention;

Fig. 2 is an enlarged detail sectional view taken along the line IIII of Fig. 1; and

Fig. 3 is a further enlargement in section of a portion of the apparatus, taken along the line IIIIII of Fig. 2.

As shown in Fig. l, the gas turbine power plant comprises an outer cylindrical casing 5 having mounted along the axis thereof an inner core structure, generally indicated at 6, forming an annular fluid passageway I which extends through the plant from a forwardly directed inlet opening 8, formed in a frontal casing section 9 carried by the outer casing 5, to a rearwardly disposed jet discharge nozzle ll]. Journaled coaxially in the core structure is a rotor aggregate comprising the rotor of an axial-flow compressor II, a shaft l2 and the rotor of a turbine l3 for driving the compressor. Interposed in the passageway 1 between the outlet of the compressor H and the inlet of the turbine I3 is an annular combustion apparatus l5; In operation, air entering the inlet opening 8 is compressed by the compressor H and supplied to the combustion apparatus 15, where fuel supplied by suitable nozzles (not shown) is burned to provide turbine motivating gases. After expansion through the turbine I3, the gases may be discharged through the nozzle ID in the form of a jet to develop a propulsive thrust.

Mounted in the casing section 9 adjacent and upstream of the usual bladed rotor of the compressor II is an annular inlet guide vane assembly ll, comprising an outer shroud ring 18 suitably secured to the casing section, and a plurality of radially disposed, circumferentially spaced vane elements [9, each of which may be suitably canted relative to the axial-flow path of air entering the inlet 8, for properly directing the air into the first compressor stage. The inner ends of the respective vane elements l9 are welded or otherwise suitably secured to an inner shroud ring 20, which is thereby held concentric with the outer ring IS, without engaging any support other than that of the vane elements, however. A central cowl or fairing 22, forming an element of the engine core structure 6, may be disposed upstream of the inlet guide vane assembly ll, as shown in Fig. 1, and supported axially of the casing section by means of several radial struts 23. The outwardly flared downstream edge of the cowl 22 is preferably spaced in alignment with the relatively freely hung inner shroud ring 20.

In accordance with the invention, application of an intermittent or pulsating torque to the inner shroud ring 20 will effect vibration and consequent bending of the vane elements l9 for dislodging any ice formed thereon during operation of the power plant. Preferably, with the outer shroud ring held rigidly in the casing, the inner shroud ring is actuated by a tangential vibratory device, such as an air vibrator, at a frequency corresponding to the natural frequency of the inlet guide vane structure.

Illustrated diagrammatically in the drawing is one form of air vibrator device comprising a valve element 25 mounted on the inner wall of the shroud ring 20 and having a substantially al radially disposed seat surface 26, and an air conduit 2'! terminating in a stationary nozzle element 28 and secured to the adjacent fairing 22 with the nozzle disposed in cooperative alignment with the seat surface. With the shroud ring 20 of the compressor inlet guide vane assembly held in its normal position, the seat surface 26 engages the nozzle element 28, as shown in Fig. 2. For supplying air under pressure to the nozzle element, the opposite end of the conduit 2'; is connected to the passageway 1 of the power plant, by way of a port 30 downstream of the compressor H, as shown in Fig. 1. A suitable valve 3! is preferably interposed in the conduit 27 for controlling the flow of air therethrough.

In operation, with the power plant in service under conditions conducive to ice formation in the compressor inlet passage, the valve 3| may be opened to effect supply of air under pressure to the nozzle 28. Upon sufficient increase in the pressure of air acting on the seat surface 26, the valve element 25 will be forced away from the nozzle element, thereby slightly turning the shroud ring 28 and consequently imparting a stress or bending load on the assembled vane elements is. The resultant sudden release of air under pressure from the nozzle 28, at a rate faster than that of replenishing flow by way of the port 36 and conduit 27, will permit return of the shroud ring 20 and vane elements E9 to the unstressed position thereof, while the seat surface 25 again engages the nozzle 28 to cut off the release of air. The pressure of air is then built up to repeat the stressing cycle. Rapid periodic repetition of this cycle will thus effect continuous vibration of the inlet guide vane assembly 1 for dislodging any ice that may have formed on the vanes.

While the invention has been shown in but one form. it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

i. In a compressor, casing structure having an inlet passage, a yieldable annular inlet guide vane assembly including radial vanes in said inlet passage, fixed outer shroud means securing the outer ends of the vanes to said casing structure, a freely disposed inner shroud ring secured only to the inner ends of said vanes, said inner shroud ring being free to oscillate relative to said outer shroud means, an element fixed to said shroud ring, and a vibrator device carried by said casing structure and cooperative with said element for effecting oscillation of said guide vane assembly for dislodging any ice formations from said vanes.

2. In a compressor, casing structure having an inlet passage and a discharge passage, a yieldable annular inlet guide vane assembly including radial vanes in said inlet passage, fixed outer shroud means securing the outer ends of the vanes to said casing structure, a freely disposed inner shroud ring secured only to the inner ends of said vanes, said vanes being suificiently flexible to yield to limited oscillation of said inner shroud ring, a valve element carried by said shroud ring, a nozzle element carried by said casing structure and having an opening disposed in a radial plane through the annular guide vane assembly, said valve element projecting from the inner shroud ring along the same plane and being normally held in seating engagement on said nozzle element through the medium of said inner shroud ring and said vanes, and means including a control valve and a conduit connecting said discharge passage to said nozzle element for. supplying fluid compressed by said compressor to said nozzle at a rate effecting periodic unseating of said valve element and consequent vibration of said inlet guide vane assembly for dislodging ice formations.

3. In a compressor, casing structure having an inlet passage, an annular inlet guide vane assembly including yieldable radial vanes, concentric outer and inner shroud rings secured to the ends of said vanes, respectively, means for supporting one of said shroud rings in said casing structure of the compressor, the other shroud ring being freely supported only through the medium of said yieldable vanes and relatively movable to a limited extent for imparting bending stress to the vane assembly, an element fixed to said other shroud ring, and a vibrator device fixed to the casing structure and operative to apply an intermittent force to said element on the last-named shroud ring for effecting periodic oscillation thereof to dislodge ice formations from said vanes.

4. In a compressor, casing structure having an annular inlet, a guide vane assembly including yieldable radial vanes, and concentric outer and inner shroud rings secured to the ends of said vanes, respectively, means securing one of said shroud rings in fixed relation with the casing structure of said compressor, the other shroud ring being freely supported only through the medium of said yieldable vanes and relatively movable to a limited extent for imparting bending stress to the vane assembly, and a vibrator device cooperative with the last-named shroud ring for effecting periodic oscillation thereof to dislodge ice formations from said vanes, said vibrator device comprising a valve element carried by said movable shroud ring and a fluid discharging nozzle element fixed to the casing structure, said valve element normally seating on said nozzle element and being intermittently unseated by the pressure of fiuid discharging therefrom.

ARNOLD H. REDDIN G.

References Cited in the file of this patent FOREIGN PATENTS Number Country Date 629,044 Great Britain Sept. 9, 1949 523,108 Great Britain July 1940 

